In recent years, the image recording material is predominated by a material particularly for forming a color image and specifically, a recording material using an inkjet system, an image recording material using a heat-sensitive transfer system, a recording material using an electrophotographic system, a silver halide light-sensitive material using a transfer system, a printing ink, a recording pen and the like are popularly used. Also, a color filter is used in a display such as LCD and PDP or in an electronic component such as CCD of photographing equipment.
In these color image recording materials or color filters, three primary color dyes (dyes or pigments) by a so-called additive or subtractive color mixing method are used for reproducing or recording a full color image, however, a dye having absorption properties capable of realizing a preferred color reproduction region and having fastness capable of enduring various use conditions is not found at present and improvements are keenly demanded.
The inkjet recording method has been abruptly spread and is further growing because the material cost is low, high-speed recording can be obtained, noises are less generated at the recording and color recording is easy.
The inkjet recording method includes a continuous system of continuously jetting out a liquid droplet and an on-demand system of jetting out a liquid droplet according to image information signals, and the ejection system therefor includes a system of ejecting a liquid droplet by applying a pressure using a piezoelectric element, a system of ejecting a liquid droplet by generating a bubble in the ink using heat, a system of using an ultrasonic wave, and a system of ejecting a liquid droplet by suction using an electrostatic force.
The ink used for inkjet recording includes an aqueous ink, an oily ink and a solid (fusion-type) ink.
The dye used in these inkjet recording inks is required to have good solubility or dispersibility in a solvent, enable high-density recording, provide good color, have fastness to light, heat and active gases in the environment (for example, oxidative gas (e.g., NOx, ozone) and SOx), exhibit excellent resistance against water and chemicals, ensure good fixing property to an image-receiving material to cause less blurring, give an ink having excellent storability, have no toxicity and high purity and be available at a low cost.
In particular, a dye having good cyan color and fastness to light and active gases in the environment, particularly oxidative gases such as ozone, is strongly demanded.
A representative skeleton of the cyan dye used in a water-soluble ink for inkjet recording is phthalocyanine or triphenylmethane.
Representative examples of the phthalocyanine dye which has been reported and is used over the widest range include phthalocyanine derivatives classified into the following (1) to (6):
(1) copper phthalocyanine-base dyes such as Direct Blue 86 and Direct blue 87 [for example, Cu-Pc-(SO3Na)m: a mixture of m=1 to 4] (Pc in this formula and used hereinafter means a phthalocyanine skeleton);
(2) Direct Blue 199 and phthalocyanine-base dyes described in JP-A-62-190273 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”), JP-A-63-28690, JP-A-63-306075, JP-A-63-306076, JP-A-2-131983, JP-A-3-122171, JP-A-3-200883, JP-A-7-138511, etc. [for example, Cu-Pc-(SO3Na)m(SO2NH2)n: a mixture of m+n=1 to 4];
(3) phthalocyanine-base dyes described in JP-A-63-210175, JP-A-63-37176, JP-A-63-304071, JP-A-5-171085, WO00/08102, etc. [for example, Cu-Pc-(CO2H)m(CONR1R2)n: m+n=a number of 0 to 4];
(4) phthalocyanine-base dyes described in JP-A-59-30874, JP-A-1-126381, JP-A-1-190770, JP-A-6-16982, JP-A-7-82499, JP-A-8-34942, JP-A-8-60053, JP-A-8-113745, JP-A-8-310116, JP-A-10-140063, JP-A-10-298463, JP-A-11-29729, JP-A-11-320921, EP-A-173476, EP-A-468649, EP-A-559309, EP-A-596383, German Patent 3,411,476, U.S. Pat. No. 6,086,955, WO99/13009, UK-A-2341868, etc. [for example, Cu-Pc-(SO3H)m(SO2NR1R2)n: m+n=a number of 0 to 4 and m≠0];
(5) phthalocyanine-base dyes described in JP-A-60-208365, JP-A-61-2772, JP-A-6-57653, JP-A-8-60052, JP-A-8-295819, JP-A-10-130517, JP-A-11-72614, JP-T-11-515047 (the term “JP-T” as used herein means a “published Japanese translation of a PCT patent application”), JP-T-11-515048, EP-A-196901, WO95/29208, WO98/49239, WO98/49240, WO99/50363, WO99/67334, etc. [for example, Cu-Pc-(SO3H) 1 (SO2NH2)m—(SO2NR1R2)n: 1+m+n=a number of 0 to 4]; and
(6) phthalocyanine-base dyes described in JP-A-59-22967, JP-A-61-185576, JP-A-1-95093, JP-A-3-195783, EP-A-649881, WO00/08101, WO00/08103, etc. [for example, Cu-Pc-(SO2NR1R2)n: n=a number of 1 to 5].
Phthalocyanine-base dyes widely used in general at present, represented by Direct Blue 87 and Direct Blue 199, are excellent in the light fastness as compared with generally known magenta dyes and yellow dyes.
The phthalocyanine-base dye provides a green-tinted color hue under acidic conditions and is improper for a cyan ink. In the case of using this dye for a cyan ink, the dye is most suitably used under conditions from neutral to alkaline. However, even when the ink is in the region from neutral to alkaline, if the material on which an image or the like is recorded is an acidic paper, the color hue of the printed matter may greatly change.
Furthermore, discoloration to a green tint or decoloration occurs due to oxidative gases such as nitrogen oxide gas and ozone, which are often taken as a problem also from an environmental issue, and this simultaneously causes reduction in the printing density.
On the other hand, the triphenylmethane-base dye provides a good color hue but is very inferior in the light fastness, resistance against ozone gas and the like.
If the use field hereafter expands and the printed matter is widely used for exhibition such as advertisement, the case of being exposed to light or active gases in the environment increases and to cope with this, a dye and an ink composition having good color hue, high light fastness and excellent resistance against active gases (for example, oxidative gas (e.g., NOx, ozone) and SOx) in the environment are more strongly demanded.
However, it is very difficult to find out a cyan dye (for example, phthalocyanine-base dye) and a cyan ink satisfying these requirements in a high level.
The phthalocyanine-base dyes imparted with ozone gas resistance are heretofore disclosed, for example, in JP-A-3-103484, JP-A-4-39365 and JP-A-2000-303009, however, none of these dyes have succeeded in satisfying both the color and the fastness to light and oxidative gases. A cyan ink product fully satisfying the requirements on the market is not yet provided.